HP41 Magnetic Cards


After letting my HP 41 sit on shelf for a number of years, I have recently had reason to attempt to rescue and use some programs I wrote back about 1981. Fortunately the card reader still works (it was repaired once some years ago by HP for the gummy drive roller problem) and seems to work OK. Unfortunately I have found that from 10 to 50% of cards for a program are unreadable. So far as I know it is only possible to read cards into memory in sequence and when one gets to an unreadable side, that is all you are going to load. I have some hardcopy listings, but entering multi-hundred keystroke programs with no errors is a challenging task. What kind of life should I reasonably expect from these cards? Is there any way to load cards past the MALFUNCTION code shown when a bad card side is attempted to be read so that one can enter only the missing program steps? Any thoughts, comments would be appreciated. Thanks.


i know this sounds like a joke, but does spitting on them ever work, or is that only the ti59 or was that a joke as well?


I cannot really answer, but I can tell that megnetic
cards that I wrote around 1985 still work just fine
to read on my machine.

Perhaps you have some alignment problem, cleaning problem
or other issue?

Cards can be read out of order, but I don't know what
happens if one in the middle is bad. I guess you
can't get at the data after that, even if it's been
read into memory.


Quite a while ago, further back than reliable memory, I had a nearly 1000 line program that req'd some 14 cards to record. one of the cards went bad, but it seems i was able to load the rest of the program. perhaps because it contained many global labels? i remember editing in the middle of the program enough to get it working again, but i think it required re-entering entire subprograms. better than rekeying the entire thing. then i bought a wand, and have added HP-IL and an 82973A ;^]

anyway, methinks this can be done, but may require some tricks like inserting temporary labels. if time permits, i will experiment around with my bad cards and see if i can rememeber exactly what i did.

best luck,


Time should not be affecting your cards. Storage conditions might. You might want to try cleaning the cards with windex and a clean cloth (in real stubborn cases you might can try alcohol, but this can remove the lubrication from the card and/or the white paint on the back side... if so, re-record the program on a good card).

Also, have you cleaned the card reader head? Also, your replaced rubber roller is almost certainly decompsing as we speak. It may seem good, but it is not.

Possibly Related Threads…
Thread Author Replies Views Last Post
  hp-41 Cards Marcel Samek 8 3,188 11-07-2013, 11:13 PM
Last Post: Garth Wilson
  re-recording original cards aj04062 2 1,519 09-15-2013, 10:32 AM
Last Post: Dieter
  magnetic strip malfunction aurelio 7 2,580 01-14-2013, 12:25 AM
Last Post: aurelio
  Series 80 EPROM cards Paul Berger (Canada) 0 1,160 12-08-2012, 07:50 PM
Last Post: Paul Berger (Canada)
  Anyone willing to read some HP41 cards? LarryLion 10 2,928 09-05-2012, 01:48 AM
Last Post: Juergen Keller
  HP 48SX Solve Equation Library Cards Mike Hein 3 1,517 08-22-2012, 01:07 PM
Last Post: Chris Dreher
  Question about magnetic cards for the HP-41C Card Reader Namir 2 1,476 08-15-2012, 12:15 PM
Last Post: Namir
  HP-67/97 Mag Cards...Can they be marketed again? Matt Agajanian 11 3,563 05-14-2012, 10:22 PM
Last Post: Dale Reed
  HP65 program cards compatibility aurelio 2 1,307 05-04-2012, 04:43 AM
Last Post: aurelio
  Replacing Rechargeable Batteries on TDS/SMI RAM cards aj04062 2 1,445 04-12-2012, 11:20 PM
Last Post: Geoff Quickfall

Forum Jump: